The present invention relates generally to movable closures and, more particularly, to overhead coiling doors, rolling gates and the like.
Closure devices for protecting openings in building structures, such as doors and windows, are frequently relied upon not only to provide security for the building structure by preventing unauthorized access to the structure, but are frequently also relied upon to protect the structure from natural climatic conditions.
One approach to minimize the effects of weather has been to use rolling, coiling and/or slatted doors or shades for the door and window openings in the building. In one form, such closures are selectively rolled up in a coil at the top of the opening and unrolled to cover the entire opening. Such systems typically include an assembly of interlocking plastic or metal slats disposed between a pair of guideways attached to opposite sides of the port or opening and the assembly is stored in a rolled-up or coiled position when the port is to be open. The slats must be allowed to freely slide along the guide tracks to a closed or open position.
These rolling closures typically flex or bend when subjected to positive or negative pressures or wind loads on the outside of the structure. Such bending and flexing of the slats effectively shorten the lengths of these slats by moving the lateral ends inwardly. This problem is particularly prevalent for larger width doors, on the order of 24 feet or so.
Some known designs have attempted to limit the lateral inward movement of the ends of the slats with detents, locks, clamps or the like to thereby prevent excessive bowing or flexing of the slats. The doors and the like are not operable under such conditions because of the increased drag and friction at the lateral ends of the slats contained in guideways surrounding the door opening, window or the like.
One alternative to minimizing or preventing the flexing or bowing of the slats is to reinforce the slats to resist the wind loads. However, reinforcing techniques often result in more expensive or heavier closures which are more difficult to easily raise and lower as desired.
As a result, there is a need for a rolling or coiling closure which is a door, shutter or the like that is capable of withstanding severe climatic conditions, increased wind loads and other forces while still being operable for movement to and between closed positions under such conditions. Further, the closure system must be economically feasible without adding significant cost, weight or other detrimental features to the design.